fix(grpc): 🐛 Fix gRPC doc generation for proto files organized in packages

[linwumingshi]

• Closes gRPC doc doesn't work if proto files organized in package #1116

• Fixes the core issue: Resolves the problem where grpc-xxx goals fail when .proto files are organized using packages (e.g., base/enum.proto, file/fileops.proto). The root cause was an incorrect --proto_path calculation.

• Enhances path handling: Refactored getUniqueParentDirectories to correctly find the deepest common ancestor directory, ensuring --proto_path points to the actual root of the .proto files.

• Improves command robustness: Uses absolute paths for protoc, protoc-gen-doc, and all input .proto files to guarantee reliable execution across different environments.

• Adds comprehensive logging: Logs the final protoc command for debugging and adds [protoc] prefix to plugin output, making it easier to distinguish between smart-doc logs and protoc errors.

[github-actions]

@linwumingshi

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Thanks for your PR. 🙏
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感谢您提交的PR。 🙏
请再次查看您的PR内容，确认是否包含任何使用方式或配置参数的变更，如：新增配置参数、修改默认配置等操作。
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另外，如果您添加了新功能，请在仓库smart-doc-group/smart-doc-example-cn中提供示例代码。这将帮助其他用户了解如何使用新功能。

代码风格提示：
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